Chapter 40 - Intro to Ecology

Ecology

scientific study of the interactions between organisms and the environment

• reveals the richness of the biosphere

• these interactions determine distribution of organisms and their abundance

• derived from the words

  • oikos (home)

  • logos (study)

types of ecology

• global ecology

• landscape ecology

• ecosystem evology

• community ecology

• population ecology

• organismal ecology

organismal ecology

studies how an organism’s structure, physiology, and behaviour meet environmental challenges

population

group of individuals of the same species living in an area

population ecology

focuses on factors affecting how many individuals of a species live in an area

community

group of populations of different species in an area

community ecology

deals with the whole array of interacting species in a community

ecosystem

community of organisms in an area and the physical factors where they interact

ecosystem ecology

emphasizes energy flow and chemical cycling among various biotic and abiotic componenets

landscape

mosaic of connected ecosystems

landscape ecology

deals with arrays of ecosystems and how they are arranged in a geographic region

biosphere

global ecosystem

• sum of all the planet’s ecosystens

global ecology

examines the influence of energy and materials on organisms across the biosphere

regional effects on climate

Seasonality

• in middle to high latitudes, Earth’s tilted axis of rotation and annual passage around the sun cause strong seasonal cycles in day length, solar radiation, and temperature

Bodies of water

• ocean currents influence climate along the coasts of continents by heating or cooling overlying air masses that pass across the land

  • coastal regions are also more wetter than inland regions

Mountains

• influence air flow over land

  • as warm air approaches a mountain, moisture is released on the windward side

biomes

major ecological associations that occupy broad geographic regions of land or water

• varying combinations of biotic and abiotic factors determine the nature of biomes

  • terrestrial biomes are defined by the vegetation type

  • aquatic biomes are defined by the physical environment

general features of terrestrial biomes

major physical or climatic features and dominant vegetation

• vertical layering of vegetation is an important feature of terrestrial biomes

• layering of vegetation creates different habitats for animals

Tropical forest Climate

Climate

• usually high temp.

• rain forests 200-400cm of rain anually

• dry forests 150-200cm of rain anually

Tropical Forest Organisms

• vertically layered forests and plants compete for light

• home to millions of species

• animal diversity higher than any other terrestrial biomes layering

Human impact on tropical forests

rapid population growth leading to agriculture and development is destroying many tropical forests

Savanna Climate

Climate

• rainfall averages 30-50cm per year and is seasonal

• temp averages 24-29*C

Savanna organisms

• scattered trees and are often thorny

• fires are common in dry season and dominant plant species are fire adapted

• grasses and forbs - primary ground cover

• large herbivorous mammals and their predators are common

human impact on Savanna

• frequent human-caused fires prevent regeneration

• cattle ranching and overhunting reduces large mammal populations

Desert climate

Climate

• low precipitation - less than 30cm of rain per year

• temp. varies seasonally and daily

  • > 50*C in hot desserts

  • < 30*C in colds desserts

Desert organisms

• dominated by low, widely scattered vegetation

• plant adaptations include tolerance to heat and desiccation, water storage, reduced leaf area, and physical defences against herbivores

human impact on desert

• long distance water transport and deep wells have allowed humans to live in desserts

• urbanization and agriculture have reduced biodiversity

Chaparral climate

Climate

• 30-50cm annual precipitation

• rainy winters, dry summers

Chaparral organisms

• shrubs - small trees that are fire adapted

  • some germinate only after fires

  • adapted to droyght

• animals: browsers like deers and goats, insects, small mammals, amphibians, birds

human impact on chaparral

• have been heavily settled and reduced through conversion to agriculture and urbanization

• Humans contribute to fires

Temperate grassland climate

climate

• annual precipitation 30-100cm

• dry winters, wet summers

temperate grassland organisms

• dominated by grasses and forbs

• plants adapted to drought, fire

• grazing by animals (bison and wild horses) prevents establish of trees

• burrowing animals are common

human impact on temperate grasslands

• many grasslands have been converted to farm and grazing lands

• grazing has converted some dry grassland to desert

Northern coniferous forest climate

Climate

• annual precipitation 30-70cm

• cold winters

• large annual temp. range

Northern coniferous forest organisms

• conifers are common

  • some depend on fire to regenerate

• plant diversity lower than broadleaf forests

• Mammals: moose, brown bears, siberian tigers

• insect outbreaks can kill trees

human impact on Northern coniferous forest

• northern forests are logged at a fast rate

• old growth forests are under threat

temperate broadleaf forest climate

• annual precip. 70-200cm

• winter low about 0*C, humid summers max 35*C

temperate broadleaf forest organisms

• dominant plants are deciduous trees

• in Australia, evergreen eucalyptus trees are common

• northern hemisphere, many mammals hibernate and birds migrate south

human impact on temperate broadleaf forests

• have been heavily settled, and destroyed by logging and land clearing

Tundra climate

• annual precip. 20-60cm in arctic tundra

• up to 100cm in alpina tundra

• cold winters, summer max 10*C

tundra organisms

• vegetation mostly herbaceous

  • mosses, grasses, and forbs

• permafrost restricts growth of plant roots

• musk oxen live here

• migratory caribou

• predators: bears, wolves, foxes, and snowy owls

human impact on tundra

• sparsely settled

• mineral and oil extraction in some areas

Division of aquatic biomes

see image

Wetlands and estuaries physical environment

Physical environment

• inundated by water at least some of year

• estuary a transition between river and sea

• highly productive habitats

wetlands and estuaries organisms

• water saturated soils favour growth of plants like cattails and sedges

• herbivores: crustaceans, aquatic insect larvae, muskrats

• predators: dragonflies, frogs, alligators, herons

• estuaries support oysters, crabs, fish

human impact on wetlands and estuaries

• drainage widespread

• filling, dredging, pollution disrupt estuaries

Lakes physical environment

• light decreases with depth

• seasonal lakes may have thermocline

• eutrophic lakes are nutrient rich

lake organisms

• rooted and floating aquatic plants in littoral zone

• phytoplankton in limnetic zone

• zooplankto grazers

• invertabrates in benthic zone

• fish in all zones with sufficien oxygen

human impact on lakes

• runoff from fertilized lands leads to eutropication

wetland

habitat that is inundated by water at least some of the time and supports plants adapted to water-saturated soil

• can develop in shallow basins, along flooded river banks, or on coasts of large lakes and seas

Prairie pothole region

stretches across southern prairies

• 750,000 cm²

• millions of depressions fill with snow melt and rain

why are wetlands good

they act like giant sponges

• soak up rain and snowmelt and release water in drier season

• reduces erosion and flooding and filter water

wetland conservation

• 2/3 of prairie wetlands are gone

• at risk to global warming

one of the most productive biomes on earth

streams and rivers physical environment

• headwaters clear and cold

• downstream water warmer and more turbid

streams and rivers organisms

• headwaters may be rich in phytoplankton or rooted aquatic plants

• diverse fishes and invertebrates inhabit unpolluted streams and rivers

human impact on streams and rivers

• municipal, agricultural, and industrial pollution degrade water quality

• dams impair natural flow of streams and rivers

intertidal zones physical environment

• periodically submerged by tides twice daily

• upper strata experience more exposure to air and greater variations in temp. and salinity

intertidal zones organisms

• diverse marine algae

• sandy zones lack attached plants or algae

• some animals adapted to attaching to rocks

• many animals in sandy or muddy areas bury themselves and feed on riding tides

human impact on intertidal zones

• oil pollution has disrupted many intertidal communities

coral reefs physical environment

physical environment

• formed largely from calcium carbonate skeletons of corals

• shallow reef building corals live in clear photic zone of tropical seas

coral reefs organisms

• unicellular algae live within tissues of corals in mutualism

  • provides coral with organic molcules

• high density of fish invertebrate in corals

• species diversity rivals tropical forests

human impact on coral reefs

• global warming and pollution contribute to large-scale coral death

oceanic pelagic zone physical environment

physical environment

• vast realm of open blue water

• surface constantly mixed by wind-driven currents

• covers 70% of earth

ocean pelagic zone organisms

• dominant photosynthetic organisms - bacteria and other phytoplankton

  • account for half of global productivity

• zooplankton eat phytoplankton

• free-swimming animals: squid, fish, sea turtles, sea mammals

human impact on ocean pelagic zone

• overfishing has depleted fish stocks

• oceans affected by climate warming and pollution

marine benthic zone

• sea floor

• temp declines and pressure increases with depth

marine benthic zone organisms

• seaweeds live in shallow benthic areas

• prokaryotes - food producers in deep sea vents

• coastal benthic communities - invertebrates and fishes

human impact on marine benthic zone

• overfishing has depleted benthic fish populations

• dumping of organic wastes creates anoxia

what limits the distribution of species

interactions between organisms and the environment

affect of dispersal on distrbution

can limit distribution due to area inaccessible or insufficient time

affect of biotic factors on distribution of species

predation, parasitism, competition, disease

affect of abiotic factors on distribution of species

physical factors - temp., light, soil structure, fire, moisture, etc.

chemical factors - water, oxygen, sainity, pH, soil nutrients, etc.

dispersal

the movement of individuals away from centers of high population density or from their area of origin

• contributes to global distribution of organisms

• natural range expansions show influence of disperson on distribution

• ex. cattle egret

species transplants

organisms that are intentionally or accidentally relocated from their original distribution

• can disrupt the communities or ecosystems they are introduced to

biotic factors that affect distribution of organisms

• interactions with other species

• predation

• competition

Abiotic factors affecting distribution

• temp.

• water and oxygen

• salinity

• sunlight

• rocks and soil

affect of temp. on distribution of organisms

• important factor due to its effects on biological processes

• cells may freeze and rupture below 0*C

• most proteins denature above 45*C

• mammals and birds use up energy to regulate internal temp.

water and oxygen affect on distribution of organisms

• water availability

• ex. desert organism adaptations for water conservation

salinity effect on distribution of organisms

salt concentration affects water balance of organisms through osmosis

• few terrestrial organisms are adapted to high-salinity habitats

sunlight affect on distribution of organisms

light intensity and quality affect photosynthesis

• water absorbs light causing most photosynthesis to occur near the surface of aquatic environments

• in deserts, high light levels increase temp. and can stress plants and animals

rocks and soils affect on distribution of organisms

• many characteristics of soil limit distribution of plants and the animals that eat them

  • physical structure

  • pH

  • mineral composition